Obviously we dont know yet.
But so far Jack thinks he doesn't have a chance with her, unless he starts all over again. And she's getting on with Sawyer all over again seeing as he's gotten over Juliet pretty quickly. Jack jumped off the boat because he doesn't want to leave the island, whereas Kate does. And Sawyer didn't want Claire to come because he wants Kate to be safe. So it's leaning towards Kate and Sawyer for now.